Reactive polyester resin based on a hydroxylated and / or epoxidized fatty acid triglyceride polyol for coatings with high solids content

Abstract

The invention relates to a hydroxylated and / or carboxylated polyester resin, which comprises in the structure thereof ester units formed from a polyol component a) comprising at least one polyol a1) chosen from hydroxylated and / or epoxidized fatty acid triglycerides of general formula (I): R-CO2-(H)C-(CH2-CO2-R)2 (I) with R being the radical of a residue, without carboxyl group, of a hydroxylated and / or epoxidized fatty acid RCO2H with R comprising 13 to 21 carbon atoms and at least one hydroxy and / or epoxy group. The invention also relates to a crosslinkable coating composition in an organic solvent medium comprising said resin as the coating which results from this use.

Description

[0001] The present invention relates to a reactive, hydroxylated and / or carboxylated polyester resin having a specific composition, characterized in particular by the selective specific choice of its polyol component and more particularly in combination with a specific choice of its polyacid component, with said polyol component comprising as polyol a hydroxylated and / or epoxidized fatty acid triglyceride (triglyceride). In particular, said polyol is free of monoalcohols and more particularly the polyacid component is free of unsaturated or saturated monofatty acids.Said resin is a solvent-based resin having a high solids content of at least 50%, preferably at least 60%, more preferably 65 to 90% and even more preferably 65 to 85% by weight and of a viscosity suitable for high solids content coatings and in particular having in addition a high yield power, more particularly for metal foil coatings ("coil coatings") or coating for metal packaging ("packaging coatings"). CN 107 828 053 ​​A relates to a polyester resin having a high solids content and a low viscosity, and used for coating inter alia metal surfaces. Example 1 of CN 107 828 053 ​​A describes the reaction between castor oil, isophthalic acid, adipic acid, glycerol, trimethylolpropane, butanediol. An organic solvent is added. The hydroxyl number of the resin is greater than or equal to 135 mg KOH / g and its molecular weight between 2200 and 3000.

[0002] WO2016 / 203136 already describes reactive, hydroxylated and / or carboxylated polyester resins having zero oil content, for high solids and high coverage coatings. No specific presence of hydroxylated and / or epoxidized fatty acid triglyceride polyol is described or suggested nor its effect on the improved performance obtained.

[0003] The objective of the present invention is therefore to improve, by the specific structure of the binder resin used, the solids content with a content by weight of at least 50% in an organic solvent medium, as mentioned above, while maintaining a viscosity of the coating composition suitable for the final application, in particular for application on metal sheets or for metal packaging. This "suitable" viscosity must be a Brookfield viscosity of less than 1000 mPa.s at the application temperature ranging from 15 to 35°C, said Brookfield viscosity being measured according to the ISO 3219 method. Concerning the resin in question, it must have a viscosity of less than 20000 mPa.s in solution in an organic solvent at 25°C with a resin content (dry extract) of 80% by weight. Concerning the high yield power of said coating comprising said resin, preferably, it is greater than 400 m 2 < per kg of coating for a thickness of 1 µm.In particular, an increase (improvement or gain in yield) of at least 8% and preferably 9 to 20% in yield power is obtained compared to a coating comprising a polyester resin which does not have the specific resin composition as defined according to the present invention. The high yield power of said coating according to the invention allows in particular a significant improvement in the anti-corrosion protection of said metal sheets or said metal packaging thus coated.

[0004] The present invention is as defined in the claims.

[0005] The present invention firstly relates to a hydroxylated and / or carboxylated polyester resin of specific structure obtained from a specific composition of polyol component a) of said resin.

[0006] The invention also relates to a solution of said resin in an organic solvent, in particular at a resin content relative to the weight of said solution of at least 50%, preferably at least 60%, in particular ranging from 60 to 90%, more preferably from 65 to 90% and even more preferably from 65 to 85%.

[0007] The invention also covers a crosslinkable composition comprising said resin, in particular a coating composition and more particularly a coating composition for metal sheets or for metal packaging.

[0008] Also covered is the use of said resin or a solution of said resin as a binder in a coating composition in an organic solvent medium, in particular for crosslinkable coatings and more particularly for increasing the yield power of said coating or for protective coatings, in particular anti-corrosion coatings for metal.

[0009] Another object of the invention is the finished product which is a coating which results from the use of said resin or a solution of said resin or a crosslinkable composition containing it, in particular having an increased (improved) yield power compared to other common polyester resins.

[0010] The first subject of the invention relates to a hydroxylated and / or carboxylated polyester resin, which comprises in its structure ester units, formed from a polyol component a) and a polyacid component b), the polyol component a) comprising at least one polyol a1) chosen from hydroxylated and / or epoxidized fatty acid triglycerides of general formula (I): R-CO 2 -(H)C-(CH 2 -CO 2 -R) 2 (I) with R being the residue radical without carboxy group, of a hydroxylated and / or epoxidized fatty acid RCO 2 H with R comprising 13 to 21, preferably 13 to 19 carbon atoms and at least one hydroxy and / or epoxy group, the resin having a hydroxy index of 10 to 120 mg KOH / g.

[0011] The resin comprises units formed from a polyol component a). In other words, this means that the resin is obtained from a composition comprising a polyol component a).

[0012] Said polyol component a) according to the invention may comprise both polyhydroxylated and / or epoxidized compounds (or derivatives), including polyepoxidized ones. In particular, epoxidized compounds are classified in the polyol component a) to the extent that they react like a polyol component with respect to a polyacid by forming ester bonds.

[0013] According to a particular option of said polyester resin, said triglyceride is chosen from triglycerides of 9- and / or 10-hydroxy stearic acid, 12-hydroxy stearic acid, 14-hydroxy eicosanoic acid, 12-hydroxy-9-octadecenoic acid and / or its epoxidized form, lesquerolic acid (14-hydroxy-11-cis-eicosenoic acid) and / or its epoxidized form or epoxidized soybean oil.

[0014] According to a particularly preferred option, said hydroxylated fatty acid is 12-hydroxy stearic acid or 12-hydroxy-9-octadecenoic acid, which means that said triglyceride is hydrogenated castor oil or non-hydrogenated castor oil, preferably hydrogenated castor oil.

[0015] More particularly, the weight ratio of said triglyceride polyol a1) relative to the weight of said resin varies from 1 to 30%, preferably from 2 to 25%, more preferably from 2 to 15%, more preferably still 3 to 12%, more preferably 4 to 10%.

[0016] For the purposes of the present invention, the expression "the weight ratio of component Y relative to the weight of the resin varies from 1 to 30%" means that the units formed from component Y represent 1 to 30% by weight of the total weight of the resin. In other words, this means that the resin is obtained from a composition comprising 1 to 30% by weight of component Y relative to the weight of the composition.

[0017] According to one embodiment, said polyol a1) represents 5 to 20%, in particular 10 to 15%, by weight of said polyol component a).

[0018] According to a more particular option of the polyester resin according to the invention, said polyol component a) comprises in addition to said polyol a1): a2) at least one C 2 to C 6 diol bearing at least one methyl side substituent, in particular (bearing) two C 1 -C 4 side substituents, preferably said diol being C 2 to C 4 .

[0019] More particularly, the weight rate of diol a2) relative to the weight of said resin varies from 0 to 50%, preferably from 20 to 40%, more preferably from 25 to 35%.

[0020] According to one embodiment, said polyol a2) represents 50 to 80%, in particular 60 to 75%, by weight of said polyol component a).

[0021] According to a more specific option of said resin, said polyol component a) further comprises: a3) at least one linear aliphatic C 2 to C 6 diol, without any side alkyl substituent and / or a cycloaliphatic C 6 to C 10 diol and / or a fatty C 32 to C 36 diol, in particular derived from a dimeric diacid of a C 32 to C 36 fatty acid.

[0022] More particularly, the weight content of the diol a3) relative to the weight of said resin varies from 0 to 20%, preferably from 2 to 15%, more preferably from 5 to 10%.

[0023] According to one embodiment, said polyol a3) represents 10 to 30%, in particular 15 to 25%, by weight of said polyol component a).

[0024] According to a particular embodiment, the polyol component a) comprises the polyol a1), the diol a2) and the diol a3).

[0025] The polyol component a) may in particular represent 20 to 60%, in particular 30 to 50%, more particularly 35 to 45%, by weight of the weight of the resin.

[0026] Even more particularly in said resin, said polyol component a) further comprises: a4) at least one polyol of functionality > 2 and preferably of functionality of 3 or 4, more preferably of 3, and that (in this case) said resin has a branched structure.

[0027] A branched structure (also called branched) means that the chain structure of said resin includes lateral polyester segments, linked to the functionality greater than 2 of the polyol a4).

[0028] Said polyol triglyceride a1) may be a triglyceride resulting from the hydrogenation of the corresponding unsaturated hydroxylated oil: the triglyceride of 12-hydroxy stearic acid from the hydrogenation of castor oil (ricinoleic acid triglyceride), the triglyceride of 14-hydroxy eicosanoic acid from the hydrogenation of the triglyceride of 14-hydroxy 11 cis-eicosenoic acid (lesquerolic acid triglyceride).

[0029] Suitable components a2) include: methyl ethylene glycol, methyl propane diol, neopentyl glycol (2,2-dimethyl 1,3-propanediol), dimethyl butane diol, 2-butyl-2-ethyl-1,3-propane diol, and preferably neopentyl glycol or 2-butyl, 2-ethyl 1,3-propane diol.

[0030] Suitable linear aliphatic diol components a3) include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butane diol, pentane diol or hexanediol, preferably ethylene glycol and hexanediol. Cycloaliphatic diol a3) includes cyclohexane diol or cyclohexane dimethanol. Fatty diol a3) includes fatty diols derived from C 32 to C 36 fatty acid dimers, with said fatty diol possibly being hydrogenated or non-hydrogenated. For example, said C 32 to C 36 fatty diols can be obtained by reduction of the carboxy groups of C 32 to C 36 fatty acid dimers, more particularly by catalytic hydrogenation of said fatty acid dimers with replacement of the carboxy groups by hydroxy groups (reduced form of the carboxy groups).

[0031] Suitable components a4) include: glycerol and trimethylol propane.

[0032] The resin according to the invention comprises in its structure ester units, formed from a polyol component a) and a polyacid component b). In other words, this means that the resin is obtained from a composition comprising a polyol component a) and a polyacid component b).

[0033] The polyacid component b) may in particular comprise diacids, diacid derivatives or anhydrides.

[0034] Even more particularly, said resin according to the invention has a polyacid component b) which comprises: b1) at least one aromatic diacid or its anhydride, preferably representing from 20 to 75% by weight of said resin, b2) optionally, at least one linear aliphatic diacid, C 4 to C 10 , preferably C 4 to C 8 , or its anhydride and / or at least one dimeric diacid of a C 32 to C 36 fatty acid, b3) optionally, at least one cycloaliphatic diacid or its anhydride.

[0035] Diacids b1), b2) and b3) may be diacid derivatives. For the purposes of the present invention, a diacid derivative is a compound that can be converted into a diacid by hydrolysis or transesterification. Diacid derivatives include partially or fully esterified forms of the diacids defined above, including C1-C6 alkyl mono- and diesters of the diacids defined above.

[0036] The polyacid component b) may in particular represent 40 to 80%, in particular 50 to 70%, more particularly 55 to 65%, by weight of the weight of the resin.

[0037] According to a particular composition of said resin, the polyacid component b) consists essentially of the diacid b1) or its anhydride.

[0038] According to a particular composition of said resin, the polyacid component b) of said resin comprises (in addition to the diacids b1) and b2)) at least one cycloaliphatic dicarboxylic acid b3) or its anhydride.

[0039] According to one embodiment, the weight content of b1) relative to the weight of said resin varies from 20 to 75%, in particular from 50 to 70%, more particularly from 55 to 65%.

[0040] As aromatic diacid b1) or its anhydride, we can cite isophthalic acid, terephthalic acid, phthalic anhydride.

[0041] As linear aliphatic diacid b2) or its anhydride, there may be mentioned malonic acid, adipic acid, succinic acid, azelaic acid or sebacic acid and as dimeric diacid of C 32 to C 36 fatty acid, a dimer of fatty acid derived from tall oil or rapeseed oil, hydrogenated or non-hydrogenated and succinic anhydride.

[0042] Examples of cycloaliphatic diacid b3) or its anhydride include cyclohexane dicarboxylic acid, hexahydrophthalic acid and hexahydrophthalic anhydride.

[0043] A "substituted Cn diol" means that it has chained carbon atoms (linked together in a chain) except for the side substituents which are not counted in the said number n. By "Cn" is meant the length of the carbon chain (-CC-) carrying the 2 hydroxy groups, the substituents being carried by these same n atoms.

[0044] The term "Cn polyacid" means that said polyacid has carbons including the carbons of the carboxy groups (-CO2H).

[0045] Said diol a2) is preferably selected from: neopentyl glycol (2,2-dimethyl-1,3-propanediol) or 2-butyl-2-ethyl-1,3-propanediol and in particular neopentyl glycol.

[0046] Preferably, said polyol a2) represents less than 75% by weight of said polyol component a).

[0047] The resin has a hydroxyl number of 10 to 120 mg KOH / g. According to a particular embodiment, the resin has a hydroxyl number of 15 to 100, 20 to 80, 25 to 75, 30 to 60 or 35 to 50 mg KOH / g.

[0048] According to a particular embodiment, the resin has a carboxy index less than or equal to 20, less than or equal to 15, less than or equal to 10, less than or equal to 7 or less than or equal to 5 mg KOH / g. The carboxy index can in particular range from 0 to 20, from 0.1 to 15, from 0.5 to 10, from 1 to 7 mg, from 2 to 5 mg KOH / g.

[0049] Preferably, said resin has a hydroxy index or a carboxy index or an overall hydroxy + carboxy index ranging from 5 to 200, preferably from 10 to 175 mg KOH / g.

[0050] Said resin according to the invention has in particular a glass transition temperature measured by DSC at 10°C / min, in two passes, from -10°C to 100°C, preferably from -10 to 50°C and more preferably from 0°C to 40°C.

[0051] According to a particularly preferred option of said resin, at least 50%, preferably at least 75% by weight of said resin is bio-sourced.

[0052] More particularly, said resin according to the invention is hydroxylated.

[0053] According to a more particular option, said resin has a number-average molecular mass Mn (calculated, in particular from the OH and acid indices and the material balance as explained further on before the experimental part) ranging from 500 to 20,000, preferably from 750 to 10,000.

[0054] According to a particular option, both components a3) and a4) are present as essential components with the other components a1) and a2) as defined above.

[0055] Said polyester resin can be prepared by polycondensation reaction of the polyol and polyacid components premixed and heated in the bulk molten state in a single step with removal of the removed water either under vacuum or in the presence of a solvent forming an azeotrope with the removed water, such as xylene. Such a process is already described in the description and examples of WO2016 / 203136. Said resin can be prepared by polycondensation reaction between the polyol component a) and the polyacid component b) as defined above. The reaction can take place in a solvent medium or in the bulk molten state, as already known to those skilled in the art. When the reaction is carried out in the presence of a solvent as an azeotropic entrainer to remove the water, the solvent preferably chosen is xylene.

[0056] The reaction is advantageously carried out in the presence of a catalyst. As catalyst, alkyl titanates such as, for example, isopropyl titanate, butyl titanate, 2-ethylhexyl titanate or tin derivatives such as, for example, tin oxide, tin oxalate, monobutyl tin oxide can be used. The amounts of catalyst used are between 100 and 5000 ppm relative to all the monomers and preferably from 500 to 1500 ppm, always relative to all the monomers.

[0057] A second subject of the invention relates to a solution of resin in an organic solvent, which solution comprises, in addition to said solvent, at least one resin as defined above according to the invention.

[0058] In particular, concerning said solution, the weight ratio of said resin relative to the total weight of resin + solvent is at least 50%, in particular at least 60% and preferably varies from 60 to 90%, more preferably from 65 to 90% and even more preferably from 65 to 85%.

[0059] As an organic solvent suitable for preparing said resin solution, said solvent may be selected from methyl esters or ethyl esters of C 2 to C 4 monocarboxylic acids or esters of said monocarboxylic acids with methoxy or ethoxy monoethers of C 2 to C 4 diols, in particular methoxy propyl acetate or from methyl or ethyl diesters of C 4 to C 6 dicarboxylic acids, terpenes, polyhydroxyalkanoates, methyl or ethyl esters of fatty acid oils or esters of lactic acid with C 4 to C 8 alcohols, aromatic solvents such as xylene or other aromatic solvents which are distillation cuts of hydrocarbons comprising 9 carbon atoms with boiling point (Bp) ranging from 155 to 180°C of the Solvarex ® type. 9 or distillation cuts of aromatic hydrocarbons containing 10 carbon atoms with an Eb point ranging from 180 to 193°C of the Solvesso ® type < 150 ND,possibly mixed with glycol monoethers such as butyl glycol (or butoxyethanol).,

[0060] Preferably, said solvent is selected from aromatic solvents, as defined above, alone or in a mixture with glycol monoethers, such as for example the mixture of a C 9 distillation cut with an Eb point ranging from 155 to 180°C such as Solvarex ®< 9 with butyl glycol. Said solvent may be the preparation solvent of said resin if prepared by polycondensation in a solvent medium or a dissolution solvent after preparation by bulk polycondensation. The solids content may be adjusted by additional addition of solvent if the resin is initially prepared in a solvent. Said solvent may be a mixture of at least two solvents from those mentioned above.

[0061] Another subject of the invention relates to a coating composition, preferably in an organic solvent medium, more particularly a crosslinkable composition, comprising at least one resin as defined above according to the invention or a resin solution as defined above.

[0062] More particularly, the coating composition according to the invention is crosslinkable and comprises, in addition to said resin, at least one crosslinking agent, carrying groups reactive with the reactive groups of said resin.

[0063] Said crosslinking agent preferably is selected from melamine, benzoguanamine or a polyisocyanate, including and in particular blocked polyisocyanate or a polyanhydride or a polysilane, in particular alkoxy-blocked polysilane when said resin is hydroxylated or said crosslinking agent is selected from polyepoxides or polyols when said resin is carboxylated.

[0064] The composition according to the invention is in particular a coating composition in an organic solvent medium. More particularly, it is a paint or varnish composition and even more particularly a paint or varnish composition for metal surfaces.

[0065] This coating composition can be applied for: finishing coatings (on primer) or single-layer coatings (direct on metal), primary coatings, backer coatings. These are coatings on the internal part of the metal sheet not exposed to the weather and light.

[0066] According to a particular preferred option, said composition comprises in addition to said resin and said crosslinking agent at least one pigment.

[0067] Another subject of the invention relates to the use of a resin or a resin solution as defined according to the invention, in coating compositions which can be crosslinked in an organic solvent medium. More particularly, according to a first option, these are coating compositions with “single-component” behavior for metal, in particular for coating on metal foil (“coil coating”) or for metal packaging (“packaging coatings”). According to a second alternative option, these are “two-component” coatings.

[0068] Said use according to the invention may also relate to powder coatings, in particular for metal.

[0069] Preferably in said use according to the invention, said coating is pigmented and said use is for coatings having a high (high) yield power for anti-corrosion protective coating.

[0070] Finally, the invention relates to a coating which results from the use of at least one resin or resin solution or coating composition as defined above according to the invention. More particularly, said coating is a metal foil coating ("coil coating") or protective coating, in particular anti-corrosion metal. Even more particularly, it may be a primary, finishing, single-layer or strip backing coating.

[0071] The measurement of the OH index is carried out according to the ISO 2554 method and that of the acid index according to the ISO 2114 method.

[0072] The value of Mn is calculated from the measured hydroxyl number and acid number which allow the calculation of an equivalent mass M eq per function (OH or carboxy or sum of the two if both present) and the number average functionality of the resin, this average functionality fm being calculated from: f m = ∑ i x i ∗ f i / ∑ i x i with xi being the number of moles of component i (acid or alcohol) and fi being the functionality of said component i the equivalent mass M eq is defined by M eq = 56000 / I OH + I acide So M n calculée = M eq * f m

[0073] The following examples are set forth below for the purpose of illustrating the invention and its performance and do not in any way limit the scope of the invention. Experimental part 1) Preparation of the resin for primary coating 1.1) Table of raw materials used (see table 1)

[0074] [Table 1] Raw material Chemical name Supplier Technical function Nature of chemical functionality Component according to the invention BANG Phthalic anhydride Polynt Monomer Carboxy / 2 Diacid b1 ISO Isophthalic acid Penpet Monomer Carboxy / 2 Diacid b1 EG Ethylene glycol Dow Monomer Hydroxy / 2 Diol a3 NPG Neopentyl glycol Perstorp Monomer Hydroxy / 2 Diol a2 HRH Hydrogenated castor oil Jayant Monomer Hydroxy / 3 Triglyceride polyol a1 Solvarex ®< 9 Aromatic solvent Total Resin solvent Resin solvent Fascat ®< 4100 Monobutyl tin oxide PMC Organometallix Catalyst Catalyst Xylene Xylene Total Azeotropic entraining solvent Azeotropic solvent 1.2) Resin preparation procedure : according to the invention (example 1) and comparative test 1, without HRH (see table 2 for proportions)

[0075] In a 1.5 l glass reactor equipped with: a Vigreux-type distillation column topped with a Dean Stark separator, a dip tube to introduce nitrogen, a temperature probe, the monomers are charged in quantities as described in Table 2 below.

[0076] The synthesis takes place at 220°C max in the presence of a catalyst (Fascat ®< 4100: 0.08 g) and xylene as an azeotropic entrainer (30 g) to remove water from the reaction.

[0077] The resin according to the invention and according to the comparative example is diluted in Solvarex ®< 9 (in addition to obtain the dry extract presented in table 2).

[0078] The characteristics of the two resins are given in Table 2.

[0079] Compositions and characteristics of the resins (excluding solvent, catalyst and azeotropic entrainer) according to the invention (example 1) and comparative test 1 [Table 2] Comparative test 1 Test according to the invention (example 1) Phthalic anhydride 203 184 Isophthalic acid 440 398 Ethylene glycol 150 69 Neopentyl glycol 207 299 HRH 0 50 TOTAL 1000 1000 Hydroxy resin value (mg KOH / g) (ISO 2554 method) 42 45 Resin acid number (mg KOH / g) (ISO 2114 method) 3,1 3,5 Dry extract (%) (ISO 3251 method) 64,7 64,5 Brookfield viscosity at 25°C (mPa.s) (ISO 3219 method) at the indicated dry extract 11200 4000 2) Preparation of the resin for the finishing coating (“top coat”) 2.1) Table of raw materials used (see table 3)

[0080] Raw materials used vs resin for top coating [Table 3] Raw material Chemical name Supplier Technical function Nature of chemical functionality Typical composition according to the invention BANG Phthalic anhydride Polynt Monomer Carboxy / 2 Diacid b1 AA Adipic acid BASF Monomer Carboxy / 2 Diacid b2 EG Ethylene glycol Dow Monomer Hydroxy / 2 Diol a3 NPG Neopentyl glycol Perstorp Monomer Hydroxy / 2 Diol a2 TMP Trimethylol propane Lanxess Monomer Hydroxy / 3 Diol a4 HRH Hydrogenated Castor Oil Jayant Monomer Hydroxy / 3 Triglyceride polyol a1 Solvarex ®< 9 Aromatic solvent Total Resin solvent Resin solvent Fascat ®< 4100 Monobutyl tin oxide PMC Organometallix Catalyst Catalyst Xylene Xylene Total Azeotropic entraining solvent Azeotropic entraining solvent 2.2) Resin preparation procedure : according to the invention (example 2) and comparative test 2 without HRH

[0081] The procedure used is identical to that described in point 1.2) (the quantities are given in table 4).

[0082] The resin according to the invention and according to the comparative example is diluted in pure Solvarex ®< 9.

[0083] The characteristics of the 2 resins are also given in Table 4. Compositions and characteristics of the resins (excluding solvent, catalyst and azeotropic entrainer) according to the invention (example 2) and comparative test 2

[0084] [Table 4] Resin component / characteristics Comparative test 2 Test according to the invention (example 2) Phthalic anhydride 450 570 Adipic acid 140 0 Ethylene glycol 70 95 Neopentyl glycol 300 280 HRH 55 Trimethylol propane 40 0 TOTAL 1000 1000 Hydroxy resin value (mg KOH / g) (ISO 2554 method) 45 35 Resin acid number (mg KOH / g) (ISO 2114 method) 3,3 2,7 Dry extract (%) (ISO 3251 method) 75,4 76 Brookfield viscosity at 25°C (mPa.s) (ISO 3219 method) at the indicated dry extract 18000 16000 3) Application of resins in paints for metal foil 3.1) Metal foil and coating application / conditioning conditions before testing

[0085] The sheet metal used for the tests is a 0.5 millimeter thick galvanized steel sheet pretreated with a chromate solution.

[0086] The paint is applied using a Bar Coater type applicator. Two types of application are carried out: primer coating, top coat,

[0087] In the case of primer coating, the paint is applied to a bare metal sheet in such a way as to obtain a film of 5 µm dry thickness.

[0088] In the case of the top coat, the paint is applied to a metal sheet coated with a 5 µm dry thickness primer coating in such a way as to obtain a top coat of 18 µm dry thickness.

[0089] The coated sheet is placed in a ventilated oven. Crosslinking conditions

[0090] [Table 5] Coating type Oven temperature (°C) Peak T (°C) of the metal / time to reach it (s) Primary 385 232 / 45 Top Coat 385 232 / 50

[0091] The primer coating, as a primary and backing coating on the metal, is evaluated using the performance tests mentioned in Table 6, after conditioning the test panels in a climate-controlled room at 23°C ± 2° where the humidity is controlled at 50% ± 5%.

[0092] The top coat is applied over the primer and the primer plus top coat system is evaluated using the performance tests listed in Table 6, after conditioning the test panels in a climate-controlled room at 23°C ± 2° where the humidity is controlled at 50% ± 5%. Coating performance tests

[0093] [Table 6] Performance testing Method used Resistance to methyl ethyl ketone(s) or methyl isobutyl ketone(s) Visual method* Load 1 Kg (MEK) or 500 g (MIBK) / linear TABER* Stamping test (mm) NF EN ISO 1520 Adhesion test NF EN ISO 2409 Adhesion + stamped 8 mm NF EN 13523-6 Adhesion + stamped 8 mm + 30 min at 90°C NF EN 13523-6 T-bend test NF EN 13523-7 PERSOZ hardness (s) NF EN ISO 1522 Condensation Tester (Q CT) with water at 40°C ISO 6270 Yield (m 2 < / Kg / µm)** Yield gain (%)*** *This method consists of going back and forth on the sheet metal with a device (TABER Abraser) soaked in solvent and noting the time from which a degradation of the coating is observed ** Yield = surface in m 2 < of metal that can be covered with 1 kg of paint having a dry thickness of 1 µm.

[0094] The yield is calculated using the following formula from the dry density of the paint, the dry extract and the layer thickness: Rendement = 1 kg . Extrait Sec % / Masse Volumique Sèche kg / m 3 / 10 − 9 m

[0095] ***Yield gain is the percentage excess yield over a standard resin (% yield improvement). 3.2) Formulation and preparation of a paint for primary coating (see table 7)

[0096] Formulation of the primer paint [Table 7] Component Quantity weight Component reference Function Supplier Chemical name Resin in solvent (invention example 1 or comparison 1) 265 (1) Tested binder see tab 2 - Polyester Solvarex ®< 9 30 (2) Solvent Total Aromatic hydrocarbon BUTYLDIGLYCOL 30 (3) Solvent Brenntag Ether alcohol DISPERBYK ®< 161 9 (4) Dispersing agent BYK Block polymer KRONOS ®< 2360 83,1 (5) Pigment KRONOS Titanium oxide SHIELDEX ®< C 303 50,3 (6) Anticorrosive pigment GRACE Silica HEUCOPHOS ®< SRPP 50,3 (7) Anticorrosive pigment Aerosil ®< R 972 6,5 (8) Rheological additive EVONIK Silica Resin in solvent (invention example 1 and comparison 1) 264 (9) Tested binder see tab 2 - Polyester CYMEL ®< 303 LF 48 (10) Crosslinker ALLNEX Melamine APTS (10% butanol w / w) 5,8 (11) Catalyst BASF Paratoluenesulfonic acid EPIKOTE 828 10,1 (12) Binder Dow Epoxy resin Solvarex ®< 9 73,95 (13) Solvent Total Aromatic hydrocarbon BUTYLDIGLYCOL 73,95 (14) Solvent Brenntag Ether alcohol Total 1000

[0097] In a 1 liter beaker thermostatically controlled at room temperature, the components (1), (2), (3), (4), (5), (6), (7), (8) are introduced in this order. This mixture is stirred using a Dispermat ® type stirrer and then dispersed for 30 minutes at 3500 rpm in the presence of glass beads to facilitate the dispersion of the pigments.

[0098] While stirring at 1000 rpm, the rest of the binder (9), components (10), (11) and (12) are added.

[0099] Still stirring at 1000 rpm, the viscosity of the paint is adjusted by adding components (13) and (14) in sufficient quantity to obtain a viscosity between 300 mPa.s and 350 mPa.s at 25°C.

[0100] The primary paint thus obtained is filtered by sieving with elimination of glass beads.

[0101] The primary paint obtained has the following characteristics (see table 8). Characteristics of the primer paint

[0102] [Table 8] Characteristic Value Dry Density (g / cm 3 < ) 1,45 % Solids (by weight) 57 (comparison 1) 62.8 (invention example 1) CPV* (%) 16 Cone-plate viscosity at 25°C (mPas) 360 (comparison 1) 350 (invention example 1) * CPV: Pigment Volume Concentration 3.2.1) Application results and performance (table 9)

[0103] [Table 9] Mechanical property Comparison 1 Invention example 1 Resistance to methyl isobutyl ketone(s) Load 500 g / TABER linear < 10 < 10 Adhesion test 0 0 Adhesion + stamped 8 mm 0 0 Adhesion + stamped 8 mm + 30 min at 90°C 0 0 T-bend test 1,5T 1T PERSOZ hardness (s) 320 325 Condensation Tester (Q CT) with water at 40°C -500 h 2S2 1S2 Yield (m 2 < / kg / µm) 393 433 Yield gain (%) - 10,1 3.3) Formulation and preparation of a paint for a top coat finish » (table 10)

[0104] List of ingredients for a tested dry extract binder adjusted to a dry extract of 70% (with respective solvents described above, respectively for resins according to invention example 2 and comparison 2) [Table 10] Component Quantity weight Component reference Function Supplier Chemical name Resin invention example 2 or comparison 2 (dry extract 70%) 226 (1) Tested binder see tab.4. Polyester Solvarex ®< 10 LN 30 (2) Solvent Total Aromatic hydrocarbon BUTYLDIGLYCOL 30 (3) Solvent Brenntag Ether alcohol DISPERBYK ®< 161 7,9 (4) Dispersing agent BYK Block polymer KRONOS ®< 2360 310 (5) Pigment KRONOS Titanium oxide Syloid ®< ED 40 26,8 (6) Charge GRACE Silica Aerosil ®< R 972 3,2 (7) Rheological additive EVONIK Silica Resin (dry extract 70%) 174 (8) Binder see tab 4 Polyester CYMEL ®< 303 LF 54,6 (9) Crosslinker ALLNEX Melamine APTS (10% butanol w / w) 11,1 (10) Catalyst BASF Paratoluenesulfonic acid Crayvallac ®< FLow 200 3 (11) Spreading agent Arkema Polyester Butyldiglycol 61,7 12) Solvent Brenntag Ether alcohol Solvarex ®< 10 LN 61,7 (13) Solvent Total Aromatic hydrocarbon Total 1000

[0105] In a 1 liter beaker thermostatically controlled at room temperature, the components (1), (2), (3), (4), (5), (6), (7) are introduced in this order. This mixture is stirred using a Dispermat type stirrer and then dispersed for 40 minutes at 3500 rpm. The rest of the binder (8) and the compound (9) are then added. The dispersion is continued for 15 minutes at 2500 rpm. Still stirring at 1000 rpm, the components (10), (11) are added, the viscosity of the paint is adjusted between 500 and 550 mPa.s by adding solvent components (12) and (13).

[0106] The “top coat” finishing coating is evaluated on a mechanical sheet previously coated with a primary coating described in 4.2).

[0107] The “top coat” (semi-gloss) finishing coating has the following characteristics (see table 11). Characteristics of the top coat

[0108] [Table 11] Dry Density (g / cm 3 < ) CPV* (%) Dry extract (%) Cone-plate viscosity at 25°C (mPas) Comparison 2 Invention example 2 Comparison 2 Invention example 2 1,75 23 63,5 71 510 500 * CPV: Pigment Volume Concentration 3.3.1) Application results and performances (table 12)

[0109] [Table 12] Feature / Test Value Resistance to methyl ethyl ketone (s) Load 1Kg / linear TABER Comparison 2 Invention example 2 > 100 > 100 Stamping test (mm) 0 0 Adhesion test 0 0 Adhesion + stamped 8 mm 2 0 Adhesion + stamped 8 mm + 30 min at 90°C 3 0 T-bend test 2T 2T PERSOZ hardness (s) 240 243 Condensation Tester (Q CT) with water at 40°C -500h 2S2 1S2 Yield (m 2 < / kg / µm)) 362 406 Yield gain (%) 0 12,1

Claims

1. Hydroxylated and / or carboxylated polyester resin, characterized in that it comprises, in its structure, ester units formed from a polyol component a) and from a polyacid component b), the polyol component a) comprising at least one polyol a1) chosen from fatty acid triglycerides:         R-CO2-(H)C-(CH2-CO2-R)2     (I) with R being the residue radical without a carboxyl group of a hydroxylated and / or epoxidized fatty acid RCO2H with R comprising from 13 to 21, preferably from 13 to 19, carbon atoms and at least one hydroxyl and / or epoxy group, the resin having a hydroxyl number of 10 to 120 mg KOH / g, measured according to the method shown in the description.

2. Polyester resin according to Claim 1, characterized in that said triglyceride is chosen from the triglycerides of 9- and / or 10-hydroxystearic acid, 12-hydroxystearic acid, 14-hydroxyeicosanoic acid, 12-hydroxy-9-octadecenoic acid and / or its epoxidized form, lesquerolic (14-hydroxy-cis-11-eicosenoic) acid and / or its epoxidized form, or epoxidized soybean oil.

3. Polyester resin according to Claim 1 or 2, characterized in that the content by weight of said polyol triglyceride a1) with respect to the weight of said resin varies from 1% to 30%, preferably from 2% to 25%, more preferentially from 2% to 15%, more preferentially from 3% to 12%, in a more preferred way from 4% to 10%.

4. Resin according to one of Claims 1 to 3, characterized in that it has a polyacid component b) which comprises: b1) at least one aromatic diacid or its anhydride, preferably representing from 20% to 75% by weight of said resin, b2) optionally, at least one linear C4 to C10, preferably C4 to C8, aliphatic diacid and / or one C32 to C36 fatty acid dimer diacid, b3) optionally, at least one cycloaliphatic diacid.

5. Resin according to one of Claims 1 to 4, characterized in that said resin has a hydroxyl number of 15 to 100, of 20 to 80, of 25 to 75, of 30 to 60 or of 35 to 50 mg KOH / g.

6. Resin according to one of Claims 1 to 5, characterized in that said resin has a carboxyl number of less than or equal to 20, of less than or equal to 15, of less than or equal to 10, of less than or equal to 7 or of less than or equal to 5 mg KOH / g.

7. Resin according to one of Claims 1 to 6, characterized in that it has a glass transition temperature, measured by DSC, at 10°C / min, of -10°C to 100°C, preferably of -10°C to 50°C and more preferentially of 0°C to 40°C.

8. Resin according to one of Claims 1 to 7, characterized in that at least 50%, preferably at least 75%, by weight of said resin is biobased.

9. Resin according to one of Claims 1 to 8, characterized in that it has a number-average molecular weight Mn, calculated according to the method shown in the description, ranging from 500 to 20 000, preferably from 750 to 10 000.

10. Solution of resin in an organic solvent, characterized in that it comprises, in addition to said solvent, at least one resin as defined according to one of Claims 1 to 9.

11. Coating composition, preferably in an organic solvent medium, preferably a crosslinkable composition, comprising at least one resin as defined according to one of Claims 1 to 9 or a resin solution as defined according to Claim 10.

12. Composition according to Claim 11, characterized in that it is crosslinkable and comprises, in addition to said resin, at least one crosslinking agent carrying groups which react with the reactive groups of said resin.

13. Use of a resin as defined according to one of Claims 1 to 9 or of a resin solution as defined according to Claim 10 in crosslinkable coating compositions in an organic solvent medium.

14. Use according to Claim 13, characterized in that it concerns coating compositions having a "one-component" behaviour for metal, in particular for coating on metal sheet (coil coating) and internal or external coating of metal packaging (packaging coating).

15. Use according to Claim 13, characterized in that it concerns "two-component" coatings.

16. Use according to Claim 13 or 14, characterized in that it concerns powder coatings.

17. Coating, characterized in that it results from the use of at least one resin as defined according to one of Claims 1 to 9 or of a resin solution as defined according to Claim 10 or of a coating composition as defined according to Claim 11 or 12.

18. Coating according to Claim 17, characterized in that it concerns a coating of metal sheet (coil coating) or internal or external coating of metal packaging (packaging coating).

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